Two-constituent polyurethance composition having high early strength

ABSTRACT

The invention relates to a two-constituent composition, wherein the first constituent (A) contains at least one polyurethane prepolymer which has isocyanate end groups and is produced from at least one aromatic polyisocyanate and at least one polyol, and at least one polyaldimine which can be obtained from at least one polyamine having aliphatic primary amino groups and at least one aldehyde which, in position α in relation to the carbonyl group, does not have any C—H groups. The second constituent (B) contains water which is bound to a carrier material. The inventive composition is characterised in that it exhibits a high early strength, and hardens quickly, thus not forming any bubbles.

TECHNICAL FIELD

The invention relates to two-component polyurethane compositions havinga high early strength, composed of a first component (A) which alsocures solely by reaction with atmospheric moisture, and a secondcomponent (B), which comprises water bound to a carrier material.

PRIOR ART

The uses to which polyurethane compositions are put include a variety ofadhesive bonds, seals and coatings. They are especially suitable foradhesive bonds or seals which require elasticity in the bond. Forcertain adhesive applications it is necessary for the bond to besubjected to a mechanical load just shortly after the adhesive has beenapplied; for example, because the bonded components are to be moved, orbecause some fixing is to be removed. In order to allow such early loadsit is advantageous for an adhesive to have a high early strength; thatis, the bond can be loaded to a certain degree even before curing iscomplete. Practical requirements on the early strength in respect oftimepoint and mechanical load vary considerably with each applicationand depend on the specific manufacturing operation, on the weight of thebonded components and on the nature of the mechanical load.

With conventional two-component polyurethane systems high earlystrengths are achievable, especially when they contain primary orsecondary amino groups in their second component. Two-componentpolyurethane compositions of this kind, however, are inconvenient todeal with, since on the one hand the defined mixing ratio of the twocomponents must be observed very precisely and on the other hand thecomponents must be mixed thoroughly and homogeneously. Otherwise theresult is a deficient adhesive bond, which fails by far to attain therequired strengths, or the system does not cure at all. Owing to thevery high reactivity of the amino groups toward the isocyanate groups,the mixing of the two components, moreover, must be very rapid andefficient and does not allow any interruptions to the operation, sinceotherwise the mixer becomes clogged. The high reactivity also results invery rapid curing and hence in very short processing times (pot livesand open times), as a result of which any careful processing, dependingon application, may be made more difficult or even impossible.

Easier to deal with are one-component polyurethane compositions. Theycomprise polyurethane prepolymers containing isocyanate end groups,which on contact with water in the form of atmospheric moisture reactand so crosslink. Since curing is accomplished by contact withatmospheric moisture, these systems cure from the outside in, the curingrate decreasing toward the inside, since the water that is needed forcuring has to diffuse through the increasingly thick layer of curedmaterial. Owing to the relatively slow curing, the early strengthsachievable with such one-component polyurethane compositions areunsatisfactory.

In order to solve the problem of the low level of water availability andhence the slow curing in a one-component polyurethane composition,systems were developed in which water, in the form of a water-containingsecond component, is mixed into a one-component polyurethanecomposition, described for example in EP 0 678 544. Although suchsystems do then have a distinctly increased curing rate, they have theserious drawback that in the course of curing they display a tendency toform disruptive bubbles, which may adversely affect the strength and theadhesion behavior of, for example, an adhesive bond. The appearance ofbubbles is a general problem of isocyanate-based systems which cure withwater, since the reaction between isocyanate groups and water releasescarbon dioxide gas (CO₂). In the case of rapid release and inadequatesolubility in the composition or excessively slow diffusion through thecomposition to the outside, this gas may accumulate in the form of gasbubbles, causing the cured material to foam to a greater or lesserdegree, which often leads to sensitive disruption of the serviceproperties.

U.S. Pat. No. 4,469,857 describes a two-component polyurethane systemcomprising in the isocyanate-based first component, which also curessolely by reaction with atmospheric moisture, polyenamines as blockedcuring agents. Polyenamines, however, generally have the drawback thatthe storage stability in combination with isocyanate compounds isinadequate, particularly in combination with reactive aromaticisocyanates such as MDI and TDI, for example.

U.S. Pat. No. 5,194,488 describes a two-component polyurethane sealantfor the adhesive bonding of automobile windows, which features rapidcuring and a relatively slow processing time, and which is composed of afirst, isocyanate-containing component with a blocked curing agent andof a second, water-containing component which releases the water in aretarded fashion. The blocked curing agent used is preferably anamine-filled molecular sieve or an enamine or ketimine or oxazolidine.The use of amine-filled molecular sieves as a blocked curing agent inpolyurethane compositions containing isocyanate groups leads, fromexperience, to distinct formation of bubbles in the course of curing.The use of molecular sieves, moreover, offers only little room formaneuver in the selection of the polyamines that can be employed, sincetheir size has to be matched to the pore size of the molecular sieve.Consequently only small diamines such as ethylenediamine come intoconsideration. Such amines exert a strong influence on the mechanicalproperties of the cured composition; the rigidity (elasticity modulus)in particular is sharply increased, which is undesirable particularlyfor flexible adhesive bonds or seals. The use of enamines or ketiminesor oxazolidines as blocked curing agents in isocyanate-based systems, onthe other hand, leads to problems with the storage stability of thefirst, isocyanate-containing component, particularly if reactivearomatic isocyanates such as MDI and TDI, for example, are present.

Practical systems in which a water-containing or water-releasing pasteis mixed to a polyurethane composition which also cures solely withmoisture and contains aromatic isocyanates, and which do not formbubbles on curing and have a high early strength, are unknown to date.

DEPICTION OF THE INVENTION

It is an object of the present invention to provide a two-componentpolyurethane composition which has a high early strength, cures rapidlyand yet does not form bubbles.

Surprisingly, it has-been found that this is achievable by means of atwo-component polyurethane composition in which the first component (A)comprises at least one polyurethane prepolymer containing isocyanate endgroups, which is prepared from at least one aromatic polyisocyanate andat least one polyol, and at least one polyaldimine which is obtainablefrom an at least one polyamine containing aliphatic primary amino groupsand at least one aldehyde which does not contain a C—H moiety positioneda to the carbonyl group, and in which the second component (B) compriseswater bound to a carrier material.

With a two-component polyurethane composition of this kind it ispossible to formulate practical systems which achieve a high earlystrength and cure rapidly without producing bubbles. Additionally andunexpectedly it has been found that despite their rapid curing suchtwo-component polyurethane compositions exhibit excellent adhesion to avariety of solids surfaces. This is all the more surprising on accountof the fact that rapid-curing reactive polyurethane systems, experiencesuggests, exhibit much poorer adhesion than those which cure slowly.Furthermore, the first component (A) alone forms a practicalone-component polyurethane composition which can be cured by atmosphericmoisture. The mechanical properties after curing of the one-componentpolyurethane composition cured slowly by atmospheric moisture,corresponding to the first component (A) of the two-componentpolyurethane composition of the invention, are of comparable qualitywith those of the two-component composition of the invention in whichwater bound to a carrier material results in rapid curing.

WAY OF IMPLEMENTING THE INVENTION

The present invention relates to a two-component composition in whichthe first component (A) comprises at least one polyurethane prepolymercontaining isocyanate end groups, which is prepared from at least onearomatic polyisocyanate and at least one polyol, and at least onepolyaldimine which is obtainable from at least one polyamine containingaliphatic primary amino groups and at least one aldehyde which does notcontain a C—H moiety positioned a to the carbonyl group, and in whichthe second component (B) comprises water bound to a carrier material.

“Poly” in “polyaldimine”, “polyol”, “polyisocyanate”, “polyamine” refersin the present document to molecules which formally contain two or moreof the respective functional groups.

The term “polyurethane” embraces in the present document all polymerswhich are prepared by the diisocyanate polyaddition process. This alsoincludes those polymers which are almost or entirely free from urethanegroups, such as polyether-polyurethanes, polyester-polyurethanes,polyether-polyureas, polyureas, polyester-polyureas, polyisocyanurates,polycarbodiimides, and so on.

The term “polyamines containing aliphatic primary amino groups” refersalways in the present document to compounds which formally contain twoor more NH₂ groups attached to an aliphatic, cycloaliphatic orarylaliphatic radical. They are therefore different from the aromaticamines in which the amino groups are attached directly to an aromaticradical, such as in aniline or 2-aminopyridine, for example.

The term “aldehyde which does not contain any C—H moiety positioned α tothe carbonyl group” refers in the present document to an aldehyde or acompound containing formyl groups in which the carbon atom positioned α(position 2) to the formyl group does not have a bond to a hydrogenatom. In other words, the aldehyde in question is an aldehyde which isnot enolizable, i.e., which does not exhibit keto-enol tautomerism.

The polyaldimine is preparable from at least one polyamine containingaliphatic primary amino groups and at least one aldehyde by acondensation reaction with elimination of water. Condensation reactionsof this kind are very well known and are described in, for example,Houben-Weyl, “Methoden der organischen Chemie”, Vol. XI/2, page 73 ff.

Suitable polyamines containing aliphatic primary amino groups forpreparing the polyaldimine include the polyamines which are known inpolyurethane chemistry, such as are used, among other things, fortwo-component polyurethanes. Examples that may be mentioned include thefollowing: aliphatic polyamines such as ethylenediamine, 1,2- and1,3-propanediamine, 2-methyl-1,2-propanediamine,2,2-dimethyl-1,3-propanediamine, 1,3- and 1,4-butanediamine, 1,3- and1,5-pentanediamine, 1,6-hexamethylenediamine, 2,2,4- and2,4,4-trimethylhexamethylenediamine and mixtures thereof,1,7-heptanediamine, 1,8-octanediamine, 4-aminomethyl-1,8-octanediamine,1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine,1,12-dodecanediamine, methylbis(3-aminopropyl)amine,1,5-diamino-2-methylpentane (MPMD), 1,3-diaminopentane (DAMP),2,5-dimethyl-1,6-hexamethylenediamine, cyclo-aliphatic polyamines suchas 1,3- and 1,4-diaminocyclo-hexane, bis(4-aminocyclohexyl)methane,bis(4-amino-3-methylcyclohexyl)methane,bis(4-amino-3-ethylcyclo-hexyl)methane,bis(4-amino-3,5-dimethylcyclohexyl)methane,1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (=isophoronediamine orIPDA), 2- and 4-methyl-1,3-diaminocyclohexane and mixtures thereof, 1,3-and 1,4-bis(aminomethyl)cyclohexane, 1-cyclohexylamino-3-amino-propane,2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptane (NBDA, produced by MitsuiChemicals), 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0^(2,6)]decane,1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA),3,9-bis(3-amino-propyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3- and1,4-xylylenediamine, aliphatic polyamines containing ether groups, suchas bis(2-aminoethyl) ether, 4,7-dioxadecane-1,10-diamine,4,9-dioxadodecane-1,12-diamine and higher oligomers thereof,polyoxyalkylene-polyamines having in theory two or three amino groups,obtainable for example under the name Jeffamine® (produced by HuntsmanChemicals), and mixtures of the aforementioned polyamines.

Preferred polyamines are 1,6-hexamethylenediamine, MPMD, DAMP, IPDA,4-aminomethyl-1,8-octanediamine, 1,3-xylylenediamine,1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane,bis(4-amino-3-methyl-cyclohexyl)methane,3(4),8(9)-bis(aminomethyl)tricyclo-[5.2.1.0^(2,6)]decane,1,4-diamino-2,2,6-trimethylcyclo-hexane, polyoxyalkylene-polyamineshaving theoretically two or three amino groups, especially Jeffamine®EDR-148, Jeffamine® D-230, Jeffamine® D-400 and Jeffamine® T-403, and,in particular, mixtures of two or more of the aforementioned polyamines.

The polyaldimine present in the composition of the invention isobtainable from at least one polyamine containing aliphatic primaryamino groups and from at least one aldehyde. It is an essential featureof the invention that said aldehyde does not contain a C—H moietypositioned α to the carbonyl group. Suitable aldehydes, accordingly, areall those which are unable to enolize and, correspondingly, thepolyaldimines prepared from them are unable to form enamines.

In a first embodiment aldehydes of the following formula (I) are used:

On the one hand Y₁, Y₂ and Y₃ here independently of one another arealkyl or arylalkyl groups each of which may optionally be substituted.

On the other hand Y₁ can be an oxy group O—Y₄, Y₄ being an optionallysubstituted alkyl or arylalkyl or aryl group, and Y₂ and Y₃independently of one another are alkyl or arylalkyl groups, each ofwhich may optionally be substituted.

Finally Y₁ and Y₂ can be connected to one another to form a carbocyclicor heterocyclic ring having a ring size of between 5 and 8, preferably6, atoms and optionally having one or two singly unsaturated bonds.

Examples of aldehydes of the formula (I) are 2,2-dimethylpropanal,2-cyclopentylpropanal, 2-cyclohexylpropanal, 2,2-diethylbutanal,3-methoxy- and 3-ethoxy- and 3-propoxy- and 3-isopropoxy and3-butoxy-2,2-dimethylpropanal, 3-(2-ethylhexoxy)-2,2-dimethyl-propanal,esters of 2-formyl-2-methylpropionic acid and alcohols such as methanol,ethanol, propanol, isopropanol, butanol and 2-ethylhexanol, ethers of2-hydroxy-2-methylpropanal and alcohols such as methanol, ethanol,propanol, isopropanol, butanol and 2-ethylhexanol, esters of2-hydroxy-2-methylpropanal and carboxylic acids such as formic acid,acetic acid, propionic acid, butyric acid, isobutyric acid and2-ethylhexanoic acid.

In another embodiment aldehydes of the following formula (II) are used:

where Y₅ is an optionally substituted ary or heteroaryl group which hasa ring size of between 5 and 8, preferably 6, atoms. The heteroatoms inthe heteroaryl ring are preferably nitrogen and oxygen.

Examples of aldehydes of the formula (II) are benzaldehyde, 2- and 3-and 4-tolualdehyde, 4-ethyl- and 4-propyl- and 4-isopropyl and4-butyl-benzaldehyde, 2,4-dimethylbenzaldehyde,2,4,5-trimethylbenzaldehyde, 4-acetoxybenzaldehyde, 4-anisaldehyde,4-ethoxybenzaldehyde, 2- and 3- and 4-formylpyridine, 2-furfuraldehyde,1- and 2-naphthylaldehyde, 3- and 4-phenyloxybenzaldehyde;quinoline-2-carbaldehyde and its 3, 4, 5, 6, 7 and 8 position isomers,anthracene-9-carbaldehyde.

In a further embodiment aldehydes of the following formula (III) areused:

For R¹ there are 3 possibilities:

R¹ firstly is a linear or branched alkyl chain, optionally containing atleast one heteroatom, in particular containing at least one etheroxygen, or is a mono- or polyunsaturated linear or branched hydrocarbonchain.

R¹ secondly is a radical of the following formula (IV):

R¹ finally is a radical of the following formula (V):

R² is a linear or branched or cyclic alkylene chain, optionallycontaining at least one heteroatom, in particular containing at leastone ether oxygen, or is a mono- or polyunsaturated linear or branched orcyclic hydrocarbon chain.

R³ is a linear or branched alkyl chain.

Examples of preferred aldehydes of the formula (III) are2,2-dimethyl-3-formoxypropanal, 2,2-dimethyl-3-acetoxypropanal,2,2-dimethyl-3-propionoxypropanal, 2,2-dimethyl-3-butyroxypropanal,2,2-dimethyl-3-isobutyroxypropanal,2,2-dimethyl-3-(2-ethylhexanoyloxy)-propanal and the aldehydes set outbelow as particularly preferred.

In one particularly preferred embodiment aldehydes of the formula (III)are used whose radicals R¹, R² and R³ are restricted as follows:

R¹ is a linear or branched alkyl chain having 11 to 30 carbon atoms,optionally containing at least one heteroatom, in particular containingat least one ether oxygen, or is a mono- or polyunsaturated linear orbranched hydrocarbon chain having 11 to 30 carbon atoms, or is a radicalof the formula (IV) or (V).

R² here is a linear or branched or cyclic alkylene chain having 2 to 16carbon atoms, optionally containing at least one heteroatom, inparticular containing at least one ether oxygen, or is a mono- orpolyunsaturated linear or branched or cyclic hydrocarbon chain having 2to 16 carbon atoms.

R³ here is a linear or branched alkyl chain having 1 to 8 carbon atoms.

This embodiment of the invention makes it possible to preparepolyurethane compositions without a disruptive odor. This is extremelyadvantageous for applications in the interior of buildings and vehiclesor in the case of application over a large surface area.

In one preferred preparation method of the aldehyde of the formula (III)3-hydroxypivalaldehyde, which can be prepared for example fromformaldehyde (or paraformaldehyde) and isobutyraldehyde, in situ ifdesired, is reacted with a carboxylic acid, in particular a long-chainfatty acid, to form the corresponding ester, specifically either withcarboxylic acid R¹—COOH to form the corresponding carboxylic ester of3-hydroxypivalaldehyde; and/or with a dicarboxylic acid monoalkyl esterHOOC—R²—COOR³ to form the aldehyde of the formula (III) with the radicalR¹ according to formula (V); and/or with a dicarboxylic acidHOOC—R²—COOH to form the aldehyde of the formula (III), in this case adialdehyde, with the radical R¹ according to formula (IV). The formulae(IV) and (V) and R¹, R² and R³ in this context have the significationalready described. This esterification can take place without the use ofsolvents by known methods, described for example in Houben-Weyl,“Methoden der organischen Chemie”, Vol. VIII, pages 516-528.

In the case of the use of dicarboxylic acids a mixture of the aldehydesof the formula (III) with the radicals R¹ according to formula (IV) andaccording to formula (V) is obtained if, for example, first some of thecarboxyl groups are esterified with 3-hydroxypivalaldehyde andthereafter the remaining carboxylic acid groups are esterified with analkyl alcohol (R³—OH). A mixture of this kind can be used furtherdirectly to prepare the polyaldimine.

Suitable carboxylic acids for esterification with 3-hydroxypivalaldehydeinclude both short-chain and long-chain carboxylic acids. Examples ofsuitable short-chain carboxylic acids are formic acid, acetic acid,propionic acid, butyric acid, isobutyric acid and 2-ethylcaproic acid.Particularly suitable are long-chain carboxylic acids such as forexample: lauric acid, tridecanoic acid, myristic acid, pentadecanoicacid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid,arachidic acid, palmitoleic acid, oleic acid, erucic acid, inoleic acid,linolenic acid, elaeostearic acid, arachidonic acid, succinic acid,glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid,sebacic acid, 1,12-dodecanedioic acid, maleic acid, fumaric acid,hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalicacid, 3,6,9-trioxaundecanedioic acid and similar derivatives ofpolyethylene glycol, dehydrogenated ricinoleic acids, and fatty acidsfrom the industrial hydrolysis of natural oils and fats, such as, forexample, rapeseed oil, sunflower oil, linseed oil, olive oil, coconutoil, oil palm kernel oil and oil palm oil.

Preference is given to lauric acid, myristic acid, palmitic acid,stearic acid, oleic acid, linoleic acid, linolenic acid, succinic acid,adipic acid, azelaic acid and sebacic acid and to technical-grade fattyacid mixtures which comprise these acids.

The reaction of at least one polyamine containing aliphatic primaryamino groups with at least one aldehyde of the formula (III) produces,for example, polyaldimines of the schematic formulae (VI) and (VII),

where n is 2, 3 or 4 and Q is intended to denote the radical of apolyamine containing aliphatic primary amino groups after all of theprimary amino groups have been removed; and

where m is an integer from 0 to 10 and Q is identical or different ateach occurrence in the same molecule and is intended in each case todenote the radical of a polyamine containing aliphatic primary aminogroups after all of the primary amino groups have been removed. Theradicals R¹ and R² in the formulae (VI) and (VII) have the significationalready described.

If a dialdehyde of the formula (III) with the radical R¹ according toformula (IV) is used for preparing a polyaldimine then it isadvantageously used either in a mixture with a monoaldehyde of theformula (III), specifically in a proportion such that, for thepolyaldimine of formula (VII), average values for m in the range from 1to 10 are obtained; or it is metered in such a way that there is anexcess of aldehyde groups in relation to the amino groups in thepreparation of the polyaldimine, the aldehyde excess being chosen suchthat for the polyaldimine of formula (VII) average values for m likewisein the range from 1 to 10 are obtained. In both ways a mixture ofoligomeric polyaldimines having a readily manipulable viscosity isobtained.

As polyaldimine it is also possible to use mixtures of differentpolyaldimines, including in particular mixtures of differentpolyaldimines prepared by means of different polyamines containingprimary aliphatic amino groups, reacted with different or the samealdehydes of the formula (I), (II) or (III). It may also be entirelyadvantageous to prepare mixtures of polyaldimines by using mixtures ofpolyamines having a different number of primary aliphatic amino groups.

For preparing the polyaldimine the aldehyde is used stoichiometricallyor in a stoichiometric excess in relation to the primary amino groups ofthe polyamine.

The two-component polyurethane composition of the invention comprises inthe first component (A) at least one polyurethane prepolymer havingisocyanate end groups, prepared from at least one aromaticpolyisocyanate and at least one polyol.

This reaction can be effected by reacting the polyol and thepolyisocyanate by customary methods, at temperatures from 50° C. to 100°C. for example, with or without the use of appropriate catalysts, thepolyisocyanate being metered such that its isocyanate groups are instoichiometric excess in relation to the hydroxyl groups of the polyol.The excess of polyisocyanate is chosen so that in the resultantpolyurethane prepolymer after all of the polyol's hydroxyl groups havereaccted there remains a free isocyanate group content of from 0.1 to15% by weight, preferably from 0.5 to 5% by weight, based on the overallpolyurethane prepolymer. If desired the polyurethane prepolymer can beprepared using solvents or plasticizers, the solvents or plasticizersused containing no isocyanate-reactive groups.

As polyols for preparing the polyurethane prepolymer it is possible forexample to use the following commercially customary polyols or anydesired mixtures thereof:

polyoxyalkylene polyols, also called polyether polyols, which arepolymerization products of ethylene oxide, 1,2-propylene oxide, 1,2- or2,3-butylene oxide, tetrahydrofuran or mixtures thereof, possiblypolymerized with the aid of a starter molecule containing two or moreactive hydrogen atoms, such as water, ammonia or compounds containingtwo or more OH or NH groups, for example, such as 1,2-ethanediol, 1,2-and 1,3-propanediol, neopentyl glycol, diethylene glycol, triethyleneglycol, the isomeric dipropylene glycols and tripropylene glycols, theisomeric butanediols, pentanediols, hexanediols, heptanediols,octanediols, nonanediols, decanediols, undecanediols, 1,3- and1,4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A,1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol, aniline andalso mixtures of the aforementioned compounds. Use may be made not onlyof polyoxyalkylene polyols which have a low degree of unsaturation(measured in accordance with ASTM D-2849-69 and stated inmilliequivalent of unsaturation per gram of polyol (meq/g)), preparedfor example by means of what are called double metal cyanide complexcatalysts (DMC catalysts), but also of polyoxyalkylene polyols having ahigher degree of unsaturation, prepared for example by means of anioniccatalysts such as NaOH, KOH or alkali metal alkoxides.

Particular suitability is possessed by polyoxyalkylene diols orpolyoxyalkylene triols, especially polyoxypropylene diols orpolyoxypropylene triols.

Of specific suitability are polyoxyalkylene diols or polyoxyalkylenetriols having a degree of unsaturation deeper than 0.02 meq/g and havinga molecular weight in the range from 1000 to 30 000 g/mol, and alsopolyoxy-propylene diols and triols having a molecular weight of from 400to 8000 g/mol.

Likewise particularly suitable are what are called “E0-endcapped”(ethylene oxide-endcapped) polyoxypropylene diols or triols. The latterare specific polyoxy-propylene-polyoxyethylene polyols obtained forexample by alkoxylating straight polyoxypropylene polyols with ethyleneoxide following polypropoxylation, and therefore having primary hydroxylgroups. By “molecular weight” or “molar weight” is meant in the presentdocument always the molecular weight average M_(n).

hydroxy-functional polybutadienes.

polyester polyols prepared for example from dihydric or trihydricalcohols such as, for example, 1,2-ethanediol, diethylene glycol,1,2-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, neopentyl glycol, glycerol, 1,1,1-trimethylolpropane ormixtures of the aforementioned alcohols with organic dicarboxylic acidsor their anhydrides or esters, such as succinic acid, glutaric acid,adipic acid, suberic acid, sebacic acid, dodedanedicarboxylic acid,maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalicacid and hexahydrophthalic acid, for example, or mixtures of theaforementioned acids, and also polyester polyols formed from lactonessuch as ε-caprolactone, for example.

polycarbonate polyols such as are obtainable by reacting, for example,the abovementioned alcohols—those use to synthesize the polyesterpolyols—with dialkyl carbonates, diaryl carbonates or phosgene.

These stated polyols have an average molecular weight of from 250 to 30000 g/mol and an average OH functionality in the range from 1.6 to 3.

In addition to these stated polyols it is possible as well to use lowmolecular weight dihydric or polyhydric alcohols such as, for example,1,2-ethanediol, 1,2- and 1,3-propanediol, neopentyl glycol, diethyleneglycol, triethylene glycol, the isomeric dipropylene glycols andtripropylene glycols, the isomeric butanediols, pentanediols,hexanediols, heptanediols, octanediols, nonanediols, decanediols,undecanediols, 1,3- and 1,4-cyclohexanedimethanol, hydrogenatedbisphenol A, dimeric fatty alcohols, 1,1,1-trimethylolethane,1,1,1-trimethylolpropane, glycerol, pentaerythritol, sugar alcohols andother higher polyhydric alcohols, low molecular mass alkoxylationproducts of the aforementioned dihydric and polyhydric alcohols, andmixtures of the aforementioned alcohols, in preparing the polyurethaneprepolymer.

The polyurethane prepolymer is prepared using commercially customaryaromatic polyisocyanates. Examples that may be mentioned include thefollowing polyisocyanates, very well known in polyurethane. chemistry:

2,4- and 2,6-tolylene diisocyanate (TDI) and any mixtures of theseisomers, 4,4′-diphenylmethane diisocyanate (MDI), the positionallyisomeric diphenylmethane diisocyanates, 1,3- and 1,4-phenylenediisocyanate, oligomers and polymers of the aforementioned isocyanates,and any desired mixtures of the aforementioned isocyanates. Particularpreference is given to MDI and TDI.

The polyurethane prepolymer and the polyaldimine are combined with oneanother, the polyaldimine being metered in an amount of from 0.1 to 1.1equivalents of aldimine groups per equivalent of isocyanate groups ofthe polyurethane prepolymer. Additionally it is possible to add acatalyst for the hydrolysis of the polyaldimine, an example being anorganic carboxylic acid such as benzoic acid or salicylic acid, anorganic carboxylic anhydride such as phthalic anhydride orhexahydrophthalic anhydride, a silyl ester of organic carboxylic acids,an organic sulfonic acid such as p-toluenesulfonic acid or4-dodecylbenzenesulfonic acid, or another organic or inorganic acid, ormixtures of the aforementioned acids.

The composition of the invention comprises a second component (B) whichcomprises water bound to a carrier material. It is a feature essentialto the invention that the water cannot be used alone. It must be boundto a carrier material. The binding, however, must be reversible; inother words, the water must be accessible for the reaction with thepolyaldimine.

The mixing of the second component (B) into the first component (A)leads to immediate availability of water in the composition as a whole,as a result of which said composition cures very much more rapidly thana one-component composition. Since the proper curing of theisocyanate-containing polyurethane with the polyaldimine under theinfluence of water is not disrupted by a stoichiometric excess of thewater in relation to the isocyanate groups and aldimine groups, andsince a substoichiometric amount of water can be compensated byaftercuring via atmospheric moisture, the functioning of the system isnot very dependent on the observance of a particular mixing ratiobetween the two components (A) and (B), such as is the case in aconventional two-component polyurethane system. For the same reasons itis also not necessary for the mixing of the two components to beentirely homogeneous. Accordingly the two-component system of theinvention is much easier to manipulate. It can be applied, for example,using apparatus which would be unsuitable for conventional two-componentpolyurethane systems.

Suitable carrier materials for component (B) may be hydrates or aquocomplexes, especially inorganic compounds having water bound incoordinative fashion or as water of crystallization. Examples of suchhydrates are Na₂SO₄.10H₂O, CaSO₄.2H₂O, CaSO₄.½H₂O, Na₂B₄O₇.10H₂O,MgSO₄.7H₂O.

Further suitable carrier materials include porous materials whichenclose water in cavities. In particular such materials are specificsilicates and zeolites. Particular suitability is possessed bykieselguhr and molecular sieves. The size of the cavities is to bechosen such that they are optimum for the accommodation of water.Consequently molecular sieves with a pore size of 4 Å are foundparticularly suitable.

A further possibility of suitable carrier materials are carriermaterials which accommodate water in nonstoichiometric amounts and havea pasty consistency or form gels. The carrier materials may be organicor inorganic. Examples thereof are silica gels, clays, such asmontmorillonite, bentonites, hectorite or polysaccharides, such ascellulose and starch, or polyacrylic acids, which are also known by thename “superabsorbents” and are employed, for example, in the productionof hygiene articles. Also suitable are carrier materials which carryionic groups.

Particularly preferred carrier materials are polyurethane polymerscontaining carboxyl groups or sulfonic acid groups as side chains and,respectively, their salts, especially their ammonium salts. Thesecarrier materials are able to accommodate and bind water until theirwater uptake capacity is exhausted.

The particularly preferred polyurethane polymers containing carboxylgroups or sulfonic acid groups and, respectively, salts thereof as sidechains may be obtained for example from polyisocyanates and polyolswhich contain carboxylic or sulfonic acid groups. The acid groups can besubsequently neutralized, in the fully reacted state, for example, withbases, especially tertiary amines. The properties of the carriermaterial are heavily dependent on the functional polyols andpolyisocyanates that are used. Account should be taken in particular ofthe hydrophilicity or hydrophobicity of the isocyanates and polyolschosen. It has been found that short-chain polyols) in particularproduce very suitable carrier materials.

For the composition of the invention it is important that the amount ofwater present in the second component (B) does not exceed theaccommodation capacity of the carrier material. The second component (B)must always—even following prolonged storage—be in the form of ahomogeneous gel or homogeneous paste and must not deposit anysubstantial quantities of liquid water.

For rapid reactions preference is given to those carrier materials whichare able to deliver the bound water rapidly. For this reason, organicpolymers containing ionic groups, in particular, are very suitablecarrier materials.

The water is released preferably at room temperature and below. It canalso be desirable, however, for the release to take place only at highertemperatures. The release temperature can be influenced greatly by thechoice of carrier material.

The ratio of equivalents of water used to equivalents of aldimine groupsused is preferably from 0.5 to 10.0, in particular from 1.0 to 5.0.

The polyurethane compositions described may further comprise, interalia, the following auxiliaries and additives well known in thepolyurethane industry: plasticizers, examples being esters of organiccarboxylic acids or their anhydrides, phthalates, such as dioctylphthalate or diisodecyl phthalate, adipates, such as dioctyl adipate,sebacates, organic phosphoric and sulfonic esters, polybutenes and othercompounds not reactive with isocyanates; reactive diluents andcrosslinkers, examples being aliphatic isocyanates such as1,6-hexamethylene diisocyanate, 2,2,4- and2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylenediisocyanate, cyclohexane 1,3- and 1,4-diisocyanate and any desiredmixtures of these isomers,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (=isophoronediisocyanate or IPDI), perhydro-2,4′- and -4,4′-diphenylmethanediisocyanate, 1,3- and 1,4-tetramethylxylylene diisocyanate,isocyanurates of these isocyanates, oligomers and polymers of theseisocyanates and also their adducts with polyols; solvents; organic andinorganic fillers, such as ground or precipitated calcium carbonates,for example, with or without a coating of stearates, especially finelydivided coated calcium carbonate, carbon blacks, kaolins, aluminas,silicas and PVC powders or hollow beads; fibers, of polyethylene forexample; pigments; catalysts such as organotin compounds, for example,such as dibutyltin dilaurate, dibutyltin dichloride, dibutyltindiacetylacetonate, organobismuth compounds or bismuth complexes, orcompounds containing amine groups, such as 2,2′-dimorpholinodiethylether, or other catalysts customary in polyurethane chemistry for thereaction of isocyanate groups; rheology modifiers such as thickeners,examples being urea compounds, polyamide waxes, bentonites or pyrogenicsilicas; adhesion promoters, especially silanes such as epoxysilanes,vinylsilanes, isocyanatosilanes and aminosilanes that are reacted withaldehydes to form aldiminosilanes, and also oligomeric forms of thesesilanes; dryers such as p-tosyl isocyanate and other reactiveisocyanates, orthoformic esters, calcium oxide or molecular sieves;stabilizers against heat, light and UV radiation; flame retardants;surface-active substances such as wetting agents, leveling agents,devolatilizers or defoamers; fungicides or substances which inhibitfungal growth; and further substances commonly used in the polyurethaneindustry, the skilled worker being clearly aware of whether theseadditional substances are suitable for both or only for one in each caseof the two components (A) and (B).

The two-component polyurethane composition of the invention also allowsin particular the formulation of white compositions which cure rapidlyand without the formation of bubbles. It is known that white systemsformulated in accordance with the prior art often exhibit extremelysevere bubble formation.

The two components, particularly the first component (A), are preparedand stored in the absence of moisture. Separately from one another thetwo components are storage-stable; that is, they can be kept in suitablepackaging or a suitable arrangement, such as in a drum, a pouch or acartridge, for example, for a period of several months up to one yearprior to their use, or longer, without losing their capacity for use. Inone embodiment the second component (B) can be kept in a container suchas is described later on below, which is integrated in a meteringattachment.

It is also possible for the two components to be charged to and storedin containers separated from one another by way of partitioning walls.Examples of such containers are coaxial cartridges or twin cartridges.

When the two components (A) and (B) are mixed the polyaldiminehydrolyzes to an aldehyde and a polyamine, the latter reacting with theisocyanate-group-containing polyurethane prepolymer and so at leastpartially curing it.

The mixing of the two components (A) and (B) takes place advantageouslycontinuously during the application. In one preferred embodiment themixing of the two components (A) and (B) takes place by means of ametering attachment which comprises two interengaging metering rotors.Preferred metering attachments of this kind are described in detail inpatent EP 0 749 530. The metering attachment is preferably mounted, forrelatively small applications, onto a commercially customary cartridge,which comprises the first component (A), while the second component (B)is located in a container which is integrated in the meteringattachment. On application, metering and mixing take place in thismetering attachment, which is operated passively by the action ofpressure on the cartridge, by means for example of a commerciallycustomary cartridge press.

For improved commixing it is possible in addition to mount a staticmixer at the exit aperture of this metering attachment.

For industrial applications, in contrast, it is advantageous to employconveying of the two components (A) and (B) from drums or hobbocks. Inthis case the two components (A) and (B) are advantageously mixed with ametering attachment which differs from the metering attachment describedabove essentially in that it has a hose connection for the secondcomponent (B).

In one embodiment the mixing of the two components (A) and (B) of thepolyurethane composition is essentially homogeneous.

In another embodiment the mixing of the two components (A) and (B) ofthe polyurethane composition is essentially layerlike.

Typical application takes place by first mixing the two components (A)and (B) of the polyurethane composition as described and then contactingthe mixed polyurethane composition with at least one solids surface andcuring it. Contacting of the solids surface takes place typically in theform of application of a bead to the surface.

Crosslinking begins immediately after the two components (A) and (B)have been mixed. Additional water, which may influence curing, maypenetrate the applied polyurethane composition from the environment, inthe form of atmospheric moisture, for example, following application.

If the polyaldimine is used in excess, i.e., if the chosen ratio of thealdimine groups to the isocyanate groups is substoichiometric, then theexcess isocyanate groups react with the water present from the secondcomponent (B) or with atmospheric moisture.

The reaction of the isocyanate-group-containing polyurethane prepolymerwith the hydrolyzing polyaldimine need not necessarily take place by wayof the polyamine. It will be appreciated that reactions withintermediates of the hydrolysis of the polyaldimine to form thepolyamine are also possible. For example, it is conceivable for thehydrolyzing polyaldimine to react in the form of a hemiaminal directlywith the isocyanate-group-containing polyurethane prepolymer.

As a consequence of the reactions described above the polyurethanecomposition cures.

The polyurethane composition described is notable for outstanding earlystrength and rapid, bubble-free cure through volume and exhibitsextremely good adhesion to a variety of solids surfaces, which in viewof the very rapid curing, is no small matter, given that experiencetells that rapid-curing polyurethane compositions have a propensity toweaknesses in their development of adhesion. The polyurethanecomposition described possesses, moreover, in the cured stateoutstanding mechanical properties. These are comparable with themechanical properties of a corresponding one-component polyurethanecomposition slowly cured by atmospheric moisture alone. The curedtwo-component polyurethane composition possesses high elongation and ahigh tensile strength in conjunction with elasticity moduli which can beadapted to the requirements of the particular application by varying thecomponents used, such as the polyols, polyisocyanates and polyamines,within a wide range.

In one preferred embodiment the aldehydes which are eliminated frompolyaldimine in the course of its hydrolysis are distinguished by thefact that in view of their high vapor pressure they remain in the curedpolyurethane composition and that they do not give rise to anydisruptive odor in so doing. Where long-chain fatty acids are used, thehydrophobic fatty acid residue has the effect of lowering the waterabsorption of the cured polyurethane composition, thereby increasing theresistance of the polyurethane material toward hydrolysis. A hydrophobicfatty acid residue, moreover, offers effective protection against theleaching of the aldehydes from the cured polyurethane composition onprolonged water contact. These polyurethane systems also have good lightstability.

The polyurethane composition described is suitable as a sealant of anykind, for the sealing for example of joints in building, as an adhesivefor the bonding of various substrates, for the bonding for example ofcomponents in the production of automobiles, rail vehicles, boats orother industrial products, and also as a coating or covering for variousarticles or variable solids surfaces.

Preferred coatings are protective applications, sealing coats,protective coatings and primer coatings. Particular preference among thecoverings is given to floor coverings. Such coverings are produced bytypically pouring a reactive composition onto the subfloor and levelingit, where it cures to form a floor covering. Floor coverings of thiskind are used for example for offices, living areas, hospitals, schools,warehouses, car parks and other private or industrial applications.These applications involve large surface areas, which even in the caseof outdoor applications can lead to occupational hygiene difficultiesand/or instances of odor nuisance. The majority of floor coverings,moreover, are applied in the interior sector. In the case of floorcoverings, therefore, the odor is generally a great problem.

The polyurethane composition is contacted at least partly with thesurface of any desired substrate. Preference is given to uniformcontacting in the form of a sealant or adhesive, a coating or acovering, specifically in the regions which for use require a connectionin the form of an adhesive bond or seal or else whose substrate is to becovered over. It may well be necessary for the substrate or the articleto be contacted to have to be subjected to physical and/or chemicalpretreatment prior to contacting, by abrasion, sandblasting, brushing orthe like, for example, or by treatment with cleaners, solvents, adhesionpromoters, adhesion promoter solutions or primers, or the application ofa tiecoat or a sealer.

EXAMPLES

Polyols Used:

Acclaim® 4200 N (Bayer): linear polypropylene oxide polyol having atheoretical OH functionality of 2, an average molecular weight of about4000, an OH number of about 28 mg KOH/g and a degree of unsaturation ofabout 0.005 meq/g.

Caradol® MD34-02 (Shell): nonlinear polypropylene oxide-polyethyleneoxide polyol, ethylene oxide-terminated, having a theoretical OHfunctionality of 3, an average molecular weight of about 4900, an OHnumber of about 35 mg KOH/g and a degree of unsaturation of about 0.08meq/g.

Caradol® ED56-11 (Shell): linear polypropylene oxide polyol having atheoretical OH functionality of 2, an average molecular weight of about2000, an OH number of about 56 mg KOH/g.

Preparation of the Polyaldimines:

Polyaldimine A1

A round-bottomed flask was charged with 62.0 g ofα,ω-polyoxypropylenediamine (Jeffamine® D-230, Huntsman; aminecontent=8.22 mmol NH₂/g). With thorough cooling and vigorous stirring,89.5 g of 2,2-dimentyl-3-isobutyroxypropanal were added from a droppingfunnel. After 10 minutes of stirring the volatile constituents weredistilled off. The reaction product thus obtained, which is liquid atroom temperature, had an aldimine content, determined as the aminecontent, of 3.58 mmol NH₂/g.

Polyaldimine A2

A round-bottomed flask was charged with 100.0 g ofα,ω-polyoxypropylenediamine (Jeffamine® D-230, Huntsman; aminecontent=8.22 mmol NH₂/g). With thorough cooling and vigorous stirring,75.0 g of isobutyraldehyde were added from a dropping funnel. After 12hours of stirring the volatile constituents were distilled off. Thereaction product thus obtained, which is liquid at room temperature, hadan aldimine content, determined as the amine content, of 5.66 mmolNH₂/g.

Polyaldimine A3

A round-bottomed flask with reflux condenser and water separator (DeanStark) was charged with 40.5 g of formaldehyde (37% in water,methanol-free), 36.0 g of isobutyraldehyde, 100.0 g of lauric acid and1.0 g of 4-toluenesulfonic acid and this initial charge was placed undera nitrogen atmosphere. The mixture was heated with vigorous stirring inan oil bath, whereupon water began to separate off. After four hours theapparatus was evacuated under a water jet vacuum. A total of around 35mL of distillate were collected in the separator. The reaction mixturewas cooled, and 48.6 g of α,ω-polyoxypropylenediamine (Jeffamine® D-230,Huntsman; amine content=8.22 mmol NH₂/g) were added from a droppingfunnel. Thereafter the volatile constituents were distilled offcompletely. The reaction product obtained in this way, which is liquidat room temperature, had an aldimine content, determined as the aminecontent, of 2.17 mmol NH₂/g.

Polyaldimine A4

A round-bottomed flask was charged with 100.0 ofα,ω-polyoxypropylenediamine (Jeffamine® D-230, Huntsman; aminecontent=8.22 mmol NH₂/g). With thorough cooling and vigorous stirring,91.0 g of benzaldehyde were added dropwise. Following the addition, themixture was stirred at room temperature for 10 minutes and then thewater was distilled off completely under a water jet vacuum. The liquidreaction product obtained in this way had an aldimine content,determined as the amine content, of 4.65 mmol NH₂/g.

Polyaldimine A5

A round-bottomed flask was charged with 50.0 of1,5-diamino-2-methylpentane (MPMD, DuPont; amine content=17.11 mmolNH₂/g). With thorough cooling and vigorous stirring, 76.0 g of2,2-dimethylpropanal were added dropwise. Following the addition, themixture was stirred at room temperature for 10 minutes and then thewater was distilled off completely under a water jet vacuum. Thereaction product obtained in this way had an aldimine content,determined as the amine content, of 7.86 mmol NH₂/g.

Preparation of the Water-Containing Component (B)

An organic polymer containing ionic groups and having an averagemolecular weight of approximately 20 000 was prepared by polyaddition ofisophorone diisocyanate (IPDI; Vestanat® IPDI, Degussa) with polyolCaradol® ED56-11 (Shell), aminoethylethanolamine and2,2-bis-(hydroxymethyl)propionic acid in N-methylpyrrolidone, followedby neutralization with triethylamine and addition of water up to a watercontent of 25% by weight. A homogeneous paste was obtained which evenafter prolonged storage remained unchanged and did not deposit anywater.

The paste prepared in this way was used as the second component (B) forall of the examples 1 to 15 described below.

Examples 1 to 7

Examples 1 to 7 demonstrate the preparation of two-componentpolyurethane compositions of the invention and their use as adhesives.

a) Preparation of the First Component (A):

In a vacuum mixer 2500 g of prepolymer 1, 1000 g of prepolymer 2, 3500 gof kaolin, 2540 g of urea thickener, 50 g of3-glycidyloxypropyltrimethoxysilane (Silquest® A-187, OSi Crompton) and10 g of benzoic acid were processed in the absence of moisture to form alump-free, homogeneous paste.

Prepolymers 1 and 2 were Prepared as Follows:

Prepolymer 1: 1295 g of polyol Acclaim® 4200 N (Bayer), 2585 g of polyolCaradol® MD34-02 (Shell), 620 g of 4,4′-methylenediphenyl diisocyanate(MDI; Desmodur® 44 MC L, Bayer) and 500 g of diisodecyl phthalate (DIDP;Palatinol® Z, BASF) were reacted by a known method at 80° C. to form anNCO-terminated polyurethane prepolymer. The reaction product had atitrimetrically determined free isocyanate group content of 2.03% byweight.

Prepolymer 2: 1230 g of polyol Acclaims 4200 N (Bayer), 615 g of polyolCaradol® MD34-02 (Shell) and 155 g of tolylene diisocyanate (TDI;Desmodur® T-80 P L, Bayer; 80:20 mixture of the 2,4 and 2,6 isomers)were reacted by a known method at 80° C. to form an NCO-terminatedprepolymer. The reaction product had a titrimetrically determined freeisocyanate group content of 1.54% by weight.

The urea thickener was prepared as follows:

A vacuum mixer was charged with 3000 g of diisodecyl phthalate (DIDP,Palatinol® Z, BASF) and 480 g of 4,4′-methylenediphenyl diisocyanate(MDI; Desmodur® 44 MC L, Bayer) and this initial charge was slightlyheated.

Then 270 g of monobutylamine were added slowly dropwise with vigorousstirring. The resultant paste was stirred for 1 hour more under vacuumand with cooling.

To prepare the first components (A) of each of Examples 1 to 7, 1000 gof this paste were subsequently admixed with the amount of polyaldimine1 listed in Table 1 for the respective example (corresponding in eachcase to the stated NH₂/NCO ratio) and this polyaldimine was mixed inhomogeneously under vacuum. TABLE 1 Amount of polyaldimine 1 and NH₂/NCOratio in the first components (A) of Examples 1 to 7. g polyaldimine 1/1000 g paste NH₂/NCO ratio Example 1 (A) 13.9 0.3 Example 2 (A) 18.5 0.4Example 3 (A) 23.1 0.5 Example 4 (A) 27.8 0.6 Example 5 (A) 32.4 0.7Example 6 (A) 37.0 0.8 Example 7 (A) 41.7 0.9

The resultant first components (A) of Examples 1 to 7 were dispensedimmediately following their preparation into aluminum cartridges havinga diameter of 45 mm, which were given an airtight seal and stored in anoven at 60° C.

b) Testing of the First Component (A):

After one day the first components (A) were tested for expression force,skinning time and volume-curing rate; after 7 days the expression forceof the first components (A) was measured again.

The expression force (EPF) of the first components (A) was determined ineach case on a freshly opened cartridge at room temperature, thepolyurethane composition being pressed through a 5 mm aperture at thetip of the cartridge at 23° C. without the addition of awater-containing component. Expression was carried out by means of atensile testing machine at a constant speed of 60 mm/min. The change inthe expression force is a measure of the storage stability of thepolyurethane composition.

The skinning time was determined by applying the first components (A),which were at room temperature, in a layer thickness of 3 mm tocardboard at 23° C. and 50% relative humidity, without adding awater-containing component, and then determining the time which elapseduntil the applied layer no longer left any residues on an LDPE pipettewhen the pipette was touched gently against its surface.

The curing rate of the first components (A) was determined at 23° C. and50% relative atmospheric humidity on a PTFE substrate.

The results of the tests performed are set out in Table 2. TABLE 2Expression force, skinning time and curing rate of the first components(A) of Examples 1 to 7. Skinning Curing EPF fresh¹ EPF stored² time rate(N) (N) (min) (mm/day) (Ref.)³ 621 820 180 3.0 Example 1 (A) 612 801 603.2 Example 2 (A) 595 788 50 3.3 Example 3 (A) 586 786 42 3.5 Example 4(A) 586 774 35 3.4 Example 5 (A) 572 757 31 3.4 Example 6 (A) 550 734 283.2 Example 7 (A) 534 731 26 3.2¹Expression force after one day of storage at 60° C.²Expression force after 7 days of storage at 60° C.³(Ref.) = reference value: same first component (A) as for Example 1 to7 but without incorporation of polyaldimine 1 and benzoic acid.

The results in Table 2 show that the first components (A) of Examples 1to 7 in the absence of moisture possess an outstanding storage stability(as good as or better than the non-polyaldimine-containing referenceadhesive) and cure even without the addition of a water-containingsecond component (B).

c) Preparation of the Two-Component Polyurethane Compositions of theInvention:

After one day of storage in an oven at 60° C. the first components (A)were heated to 80° C. and were applied with admixing of the secondcomponent (B), which is at room temperature.

The two components (A) and (B) were mixed continuously in the course ofapplication by means of a metering attachment of the Sika® Booster type(available from Sika Schweiz AG), where the substance present in theintegrated container had been replaced by the second component (B). TheSika® Booster thus modified was mounted on a cartridge comprising thefirst component (A) of the respective example and was operated passivelyby the pressure exerted on the cartridge by means of a commerciallycustomary cartridge press. A static mixer having a diameter of 16 mm and6 mixing elements, corresponding to a mixing path of 70 mm, was screwedonto the exit aperture of the modified Sika® Booster. This mixingapparatus meant that the mixing of the two components (A) and (B) of thetwo-component polyurethane composition was essentially layerlike. Theamount of the second component (B) added was 2% by weight, based on thefirst component (A).

d) Testing of the Two-Component Polyurethane Compositions of theInvention as Adhesives:

Immediately after their preparation, the two-component polyurethanecompositions of the invention were tested for open time, early strengthand bubble formation, for mechanical properties after curing, and foradhesion properties.

In order to determine the open time, i.e. the maximum possible time inwhich the adhesive following its application can still be worked—bybrushing, for instance, or by press application to an article or to asolids surface to be bonded, the adhesive was applied in the form of atriangular bead with a cross section of about 1 cm to an LDPE sheet andthen the bead was pretreated at regular intervals of time with a glassplatelet which prior to use had been pretreated with Sika® Aktivator(available from Sika Schweiz AG) and flashed off for 10 minutes, theglass plate was immediately pressed in to an adhesive thickness of about5 mm and inscribed with the time which elapsed between application ofthe bead and pressing-in of the platelet. After curing had been carriedout at 23° C. and 50% relative atmospheric humidity for one day, theadhesion between adhesive and glass was determined by removing theadhesive layer, as described later on below. The last of the glassplatelets which still showed a completely cohesive adhesion pattern thenindicated the open time.

The early strength was determined as follows. First two glass plateletsmeasuring 40×100×6 mm were pretreated on the side intended for adhesionwith Sika® Aktivator (available from Sika Schweiz AG). After a flash-offtime of 10 minutes the adhesive was applied as a triangular bead alongthe long edge of one of the glass platelets. After about one minute theapplied adhesive was pressed to a thickness of 5 mm (corresponding to abond width of about 1 cm) using the second glass platelet, by means of atensile machine (Zwick), and then stored at 23° C. and 50% relativeatmospheric humidity. After 60, 120 and 240 minutes respectively threeof the bonded glass platelets per batch were pulled apart at a tensilespeed of 200 mm/min, the maximum force required for this was recorded inN/cm bead length and the result was averaged over the three samples.

Formation of bubbles was determined as follows. The adhesive was appliedas a triangular bead with a diameter of about 1 cm to a glass plateletwhich prior to use had been pretreated with Sika® Aktivator (availablefrom Sika Schweiz AG) and flashed off for 10 minutes, the triangularbead the bead was covered with an LDPE strip and the strip was pressedin to an adhesive thickness of 5 mm. After the adhesive had cured at 23°C. and 50% relative atmospheric humidity for one day the adhesive wascut open and a qualitative assessment was made on the basis of theamount of bubbles visible to the eye, both in the adhesive and in theadhesion face between glass and adhesive.

The results of the tests performed are set out in Table 3. TABLE 3 Opentime, early strength and bubble formation of the two-componentpolyurethane compositions of the invention from examples 1 to 7. Earlystrength (N/cm) Open time after after after Bubble (min) 60 min 120 min240 min formation (Ref.)⁴ >30 1.8 2.2 7.1 none Example 1 28 3.6 5.8 14.8none Example 2 24 7.3 13.6 25.7 none Example 3 22 10.7 32.4 70.9 noneExample 4 22 23.0 70.2 152.0 none Example 5 20 30.9 83.6 166.0 noneExample 6 20 30.5 85.3 169.3 none Example 7 18 30.2 85.8 169.7 none⁴(Ref.) = reference value: same adhesive as for examples 1 to 7 butfirst component (A) without polyaldimine 1 or benzoic acid.

The results in Table 3 show that the two-component polyurethanecompositions of the invention from examples 1 to 7, in contrast to thenon-polyaldimine-containing reference adhesive, possess good tooutstanding early strength values after from one to 4 hours followingtheir application. This is particularly pronounced for examples 3 to 7,particularly 4 to 7 (NH₂/NCO ratio=0.6 to 0.9), which after 4 hours hadearly strength values which come close to the values for the strengthafter full curing. The rapid development of strength is not to thedetriment of the open time, which for all of the examples is long enoughfor practical processing. Similarly, despite the very rapid curingreaction, no disruptive gas bubbles are formed, such as is otherwiseoften the case in rapid moisture-curing polyurethane compositions, whereit frequently leads to detractions in the mechanical properties and inthe adhesion.

The mechanical properties of the adhesives were determined by applyingthe adhesive in the form of a film with a thickness of approximately 2mm to a PTFE substrate, curing the film at 23° C. and 50% relativeatmospheric humidity for 7 days and then testing it in accordance withDIN EN 53504 for tensile strength, breaking elongation and elasticitymodulus at 0.5 to 5% elongation (tensile speed: 200 mm/min).

The results of the tests performed are set out in Table 4. TABLE 4Mechanical properties of the two-component polyurethane compositions ofthe invention from examples 1 to 7. Tensile Tensile Elasticity shearBreaking strength modulus strength elongation (MPa) (MPa) (MPa) (%)(Ref.)⁵ 4.6 3.7 2.2 220 Example 1 4.5 3.4 2.7 250 Example 2 4.3 3.4 3.0230 Example 3 4.6 3.6 3.1 250 Example 4 4.5 3.3 3.2 250 Example 5 4.53.3 3.0 250 Example 6 4.5 3.3 3.5 280 Example 7 4.5 3.4 3.6 260⁵(Ref.) = reference value: same adhesive as for examples 1 to 7 butfirst component (A) without polyaldimine 1 or benzoic acid.

The results in Table 4 show that the two-component polyurethanecompositions of the invention from examples 1 to 7, after full curing,possess very good values for the mechanical properties. The values forall of the examples, irrespective of the NH₂/NCO ratio chosen, differonly slightly from those for the non-polyaldimine-containing referenceadhesive; in particular there is no unwanted increase in the values forthe elasticity modulus.

For the adhesion tests the respective solids surface was precleaned withisopropanol (acrylate topcoat, Autocryl Plus white, Akzo Nobel) orabraded with abrasive wool (plain aluminum, AlMgSi1, Rocholl,Schönbrunn, Germany; hot-dip-galvanized steel, plain, hot-dip-galvanizedST 02 Z 275-NA, Rocholl), pretreated with Sika® Aktivator (availablefrom Sika Schweiz AG) and then after a 10-minute flash-off time theadhesive was applied as a triangular bead with a diameter of about 1 cm,the bead was overlaid with an LDPE strip and the strip was pressed ongently. After 7 days of storage at 23° C. and 50% relative atmospherichumidity (indicated as “RT” in Table 5) and a further 7 days at 70° C.and 100% relative atmospheric humidity (indicated as “CC” (condensationconditions) in Table 5) the adhesion was tested by means of the “beadtest”. In this test an incision is made at the end just above theadhesion face. The incised end of the bead is held with round-endtweezers and pulled from the surface. This is done by carefully rollingup the bead on the tip of the tweezers, and placing a cut vertical tothe bead-drawing direction down to the bare surface. The rate of removalof the bead is to be chosen such that a cut has to be made about every 3seconds (cut spacing about 2 to 3 mm). The test length must amount to atleast 8 cm. The adhesion properties are evaluated on the basis of theadhesive which remains after the bead has been removed from the surface(cohesive fracture), specifically by estimating the cohesive proportionof the adhesion face in accordance with the following scale:

-   -   1=more than 95% cohesive fracture    -   2=75-95% cohesive fracture    -   3=25-75% cohesive fracture    -   4=less than 25% cohesive fracture    -   5=adhesive fracture

Test results with cohesive fracture values of less than 75% areconsidered to be inadequate.

The results of the tests performed are set out in Table 5. TABLE 5Adhesion of the two-component polyurethane compositions of the inventionfrom examples 1 to 7 on different solids surfaces Acrylic topcoatAluminum Steel RT CC RT CC RT CC (Ref.)⁶ 1 1 1 1 1 1 Example 1 1 1 1 1 11 Example 3 1 1 1 1 1 1 Example 5 2 1 1 1 1 1⁶(Ref.) = reference value: same adhesive as for examples 1 to 7 butfirst component (A) without polyaldimine 1 or benzoic acid.

The results in Table 4 show that the two-component polyurethanecompositions of the invention from examples 1 to 7 exhibit outstandingadhesion on different substrates. Despite the very rapid development ofstrength, which in the case of conventional moisture-curing polyurethanecompositions is known to lead often to adhesion detractions, they aretherefore no different in their adhesion behavior from the referenceadhesive formulated without polyaldimine.

Comparative Example 8 (Comp. 8)

As described for examples 1 to 7, 1250 g of prepolymer 1, 500 g ofprepolymer 2, 1750 g of kaolin, 1240 g of urea thickener, 25 g of3-glycidyloxypropyltrimethoxysilane (Silquest® A-187, OSI Crompton) and50 g of catalyst solution 1 were processed to a homogeneous paste.

Prepolymers 1 and 2 and the urea thickener were prepared as described inexamples 1 to 7.

Catalyst solution 1 was prepared as follows:

10 g of 2,2′-dimorpholinodiethyl ether (DMDEE) and 1 g of dibutyltindilaurate (DBTDL; Metatin® catalyst 712, Acima/Rohm & Haas; tin content18.5% by weight) were combined with 89 g of diisodecyl phthalate (DIDP;Palatinol® Z, BASF) and mixed to form a homogeneous solution.

The resulting first component (A) was dispensed immediately followingits preparation into aluminum cartridges having a diameter of 45 mm,which were given an airtight seal and stored in an oven at 60° C. Afterone day the first component (A) was tested for expression force, asdescribed in examples 1 to 7. After 7 days the expression force wasmeasured again.

After one day of storage in an oven at 60° C. the first component (A)was heated to 80° C. and with addition of the second component (B),which is at room temperature, was applied as described for examples 1 to7. The adhesive obtained as a result was tested for early strength andbubble formation, as described for examples 1 to 7.

The results of the tests performed are set out in Table 6. TABLE 6Properties of the first component (A) and of the two- componentpolyurethane composition of comparative example comp. 8. Early strengthEPF fresh⁷ EPF stored⁸ after comp. (A) comp. (A) 240 min. Bubbles (N)(N) (N/cm) formed Comp. 8 603 860 35.3 very many⁹⁷Expression force after one day of storage at 60° C.⁸Expression force after 7 days of storage at 60° C.⁹Bubbles are present in particular in the adhesion face between glassand adhesive (leads to adhesive fracture under load).

The results in Table 6 show that the two-component polyurethanecomposition of comparative example 8, which is accelerated byconventional NCO catalysis by means of an amine/tin catalyst, tendsgreatly to form bubbles on application. As a result the mechanicalproperties after curing and in particular the adhesion properties(adhesion force) of the adhesive are massively adversely affected, whichcan lead to a functional failure of an adhesive bond.

Comparative Examples 9 to 12 (Comp. 9 to Comp. 12)

As described for examples 1 to 7, 1250 g of prepolymer 1, 500 g ofprepolymer 2, 1750 g of kaolin, 1240 g of urea thickener, 25 g of3-glycidyloxypropyltrimethoxysilane (Silquest® A-187, OSI Crompton) and10 g of benzoic acid were processed to a homogeneous paste.

Prepolymers 1 and 2 and the urea thickener were prepared as described inexamples 1 to 7.

For each of comparative examples comp. 9 to comp. 12, subsequently, 1000g of this paste were admixed with the amount of a blocked curing agentset out in Table 7 for the respective example (in an NH₂/NCO ratio of0.70 for all of the examples) and this curing agent was mixed inhomogeneously under vacuum and in the absence of moisture.

The resulting first components (A) were dispensed immediately followingtheir preparation into aluminum cartridges having a diameter of 45 mm,which were given an airtight seal and stored in an oven at 60° C. Afterone day the first components (A) were tested for expression force, asdescribed in examples 1 to 7. After 7 days the expression force wasmeasured again.

After one day of storage in an oven at 60° C. the first components (A)were heated to 80° C. and with addition of the second component (B),which is at room temperature, were applied as described for examples 1to 7. The adhesive obtained as a result was tested for bubble formation,as described for examples 1 to 7.

The results of the tests performed are set out in Table 7. TABLE 7 Typeand amount of blocked curing agent in the first component (A),expression force and bubble formation of the two-component polyurethanecompositions of comparative examples comp. 9 to comp. 12. g EPF EPFcuring comp. comp. Blocked curing agent/ (A) (A) agent in comp. 1000 gfresh¹⁰ stored¹⁰ Bubbles (A) paste (N) (N) formed Comp. 9 polyaldimine 220.3 1290 >2500 none Comp. 10 polyketimine¹² 19.3 1750 >2500 none Comp.11 polyoxazolidine¹³ 27.9 1330 >2500 none Comp. 12 ethylenediamine/ 69.0580 780 many molecular sieve¹⁴¹⁰Expression force after one day of storage at 60° C.¹¹Expression force after 7 days of storage at 60° C.¹²Isophoronedi (methyl isobutyl ketimine), CAS 66230-21-5 (Desmophen ®LS 2965, Bayer).¹³Härter OZ (Bayer).¹⁴Prepared by suspending 10 g of ethylenediamine and 90 g of activatedmolecular sieve (4 Å) in 100 g of diisodecyl phthalate (DIDP;Palatinol ® Z, BASF) and stirring at 23° C. for 2 days.

The results in Table 7 show that the two-component polyurethanecompositions of comparative examples comp. 9 to comp. 12 all haveweaknesses as compared with the two-component polyurethane compositionsof the invention from examples 1 to 7. Although the two-componentpolyurethane compositions of comparative examples comp. 9 to comp. 11 docure without bubbles, their first components (A) are all not stable onstorage, since they include, as blocked curing agents, substances whicheven in the absence of water react with aromatic isocyanates. Thepolyaldimine 2 used in comparative example comp. 9 is synthesized froman aldehyde which has a C—H group positioned a to the formyl group. Incomparative examples comp. 10 and comp. 11 there are two blocked curingagents known from their use in PU coating materials; in comparativeexample comp. 10 there is a polyketimine, and in comparative examplecomp. 11 a polyoxazolidine. In comparative example comp. 12, in turn,the first component (A), comprising as blocked curing agent a diaminebound to molecular sieve, is indeed stable on storage; however, theadhesive obtained after the second component (B) has been mixed in showsa tendency to form bubbles, which adversely affect its mechanicalproperties after curing and may result in weaknesses in the adhesionbehavior.

Example 13

This example demonstrates the preparation of a two-componentpolyurethane composition of the invention and its use as an adhesive.

In a vacuum mixer 1000 g of prepolymer 1, 1250 g of prepolymer 3, 1250 gof carbon black, 600 g of kaolin, 250 g of diisodecyl phthalate (DIDP;Palatinol® Z, BASF), 300 g of urea thickener, 25 g of3-glycidyloxypropyltrimethoxysilane (Silquest® A-187, OSi Crompton), 325g of polyaldimine 3 (i.e., NH₂/NCO=0.66) and 5 g of benzoic acid wereprocessed in the absence of moisture to form a lump-free, homogeneouspaste.

Prepolymer 1 and the urea thickener were prepared as described inExample 1.

Prepolymer 3 was prepared as follows:

1770 g of polyol Acclaim® 4200 N (Bayer) and 230 g of4,4′-methylenediphenyl diisocyanate (MDI; Desmodur® 44 MC L, Bayer) werereacted by a known method at 80° C. to form an NCO-terminatedpolyurethane prepolymer. The reaction product had a titrimetricallydetermined free isocyanate group content of 1.97% by weight.

The resulting first component (A) was dispensed immediately followingits preparation into aluminum cartridges having a diameter of 45 mm,which were given an airtight seal and stored in an oven at 60° C. Afterone day the first component (A) was tested for expression force, asdescribed in examples 1 to 7. After 7 days the expression force wasmeasured again.

After one day of storage in an oven at 60° C. the first component (A)was heated to 80° C. and with addition of the second component (B),which is at room temperature, was applied as described for examples 1 to7. The adhesive obtained as a result was tested for bubble formation andalso for its mechanical properties after curing, as described forexamples 1 to 7.

The results of the tests performed are set out in Table 8. TABLE 8Expression force of the first component (A), bubble formation andmechanical properties of the two-component polyurethane composition ofthe invention from example 13. EPF EPF comp. comp. (A) (A) TensileElasticity Breaking fresh¹⁵ stored¹⁶ Bubbles strength modulus elongation(N) (N) formed (MPa) (MPa) (%) (Ref.)¹⁷ 1220 1740 many 8.1 7.3 360Example 1115 1580 none 7.9 6.8 500 13¹⁵Expression force after one day of storage at 60° C.¹⁶Expression force after 7 days of storage at 60° C.¹⁷(Ref.) = reference value: same adhesive as for example 13 but firstcomponent (A) without polyaldimine 1 or benzoic acid, instead withadditionally 150 g of diisodecyl phthalate (DIDP; Palatinol ® Z, BASF)and with 50 g of catalyst solution 1 from example 8.

The results in Table 8 show that the first component (A) of thetwo-component polyurethane composition of the invention from example 13possesses a similarly good storage stability as the polyaldimine-freefirst component (A) of the reference adhesive, accelerated byconventional NCO catalysis by means of an amine/tin catalyst. Incontrast to the reference adhesive, which is susceptible to bubbles, theadhesive of the invention cures completely without bubbles. After fullcuring it possesses very good values for the mechanical properties. Thevalues differ only slightly from those for the reference adhesive; inparticular there is no unwanted increase in the values for theelasticity modulus. At no time does the adhesive of example 13 exhibit adisruptive odor.

Examples 14 and 15

These examples demonstrate the preparation of two-component polyurethanecompositions of the invention and their use as adhesives.

As described for example 13, 1000 g of prepolymer 1, 1250 g ofprepolymer 3, 1250 g of carbon black, 600 g of kaolin, 250 g ofdiisodecyl phthalate (DIDP; Palatinol® Z, BASF), 300 g of urea thickenerand 25 g of 3-glycidyloxypropyltrimethoxysilane (Silquest® A-187, OSiCrompton) were processed in the absence of moisture to form a lump-free,homogeneous paste.

Prepolymer 1 and the urea thickener were prepared as described inExample 1, prepolymer 3 as described in example 13.

For preparing the first components (A) of each of examples 14 and 15,subsequently 1000 g of this paste were admixed with the type and amountof acid catalyst and polyaldimine set out in Table 9 for the respectiveexample (corresponding in each case to the stated NH₂/NCO ratio) andthese components were mixed in homogeneously under vacuum. TABLE 9 Typeand amount of acid catalyst and polyaldimine, and NH₂/NCO ratio in thefirst components (A) of examples 14 and 15. Acid catalyst, Polyaldimine,g/1000 g NH₂/NCO g/1000 g paste paste ratio Example 14 (A) salicyclicpolyaldimine 4, 32.4 0.66 acid, 5 Example 15 (A) benzoic acid, 5polyaldimine 5, 19.2 0.66

The first components (A) obtained in this way were dispensed immediatelyfollowing their preparation into aluminum cartridges having a diameterof 45 mm, which were given an airtight seal and stored in an oven at 60°C. After one day the first components (A) were tested for expressionforce, as described in examples 1 to 7. After 7 days the expressionforce was measured again.

After one day of storage in an oven at 60° C. the first components (A)were heated to 80° C. and with addition of the second component (B),which was at room temperature, were applied as described for examples 1to 7. The adhesives of the invention obtained in this way were testedfor bubble formation and for their mechanical properties after curing,as described for examples 1 to 7.

The results of the tests performed are set out in Table 10. TABLE 10Expression force of the first components (A), bubble formation andmechanical properties of the two-component polyurethane compositions ofthe invention from examples 14 and 15 EPF EPF comp. comp. (A) (A)Tensile Elasticity Breaking fresh¹⁸ stored¹⁹ Bubbles strength moduluselongation (N) (N) formed (MPa) (MPa) (%) Example 1140 1600 none 7.7 6.2620 14 Example 1180 1620 none 8.9 8.0 490 15¹⁸Expression force after one day of storage at 60° C.¹⁹Expression force after 7 days of storage at 60° C.

The results in Table 10 show that the first components (A) of examples14 and 15 possess good storage stability. The two-component polyurethanecompositions of the invention from examples 14 and 15 cure entirelywithout bubbles and after full curing possess very good values for themechanical properties.

1. A two-component polyurethane composition in which the first component(A) comprises at least one polyurethane prepolymer containing isocyanateend groups, which is prepared from at least one aromatic polyisocyanateand at least one polyol, and at least one polyaldimine which isobtainable from at least one polyamine containing aliphatic primaryamino groups and at least one aldehyde which does not contain a C-Hmoiety positioned a to the carbonyl group; and the second component (B)comprises water bound to a carrier material.
 2. A two-componentpolyurethane composition as claimed in claim 1, characterized in thatthe aldehyde has the formula

where Y₁, Y₂ and Y₃ independently of one another are optionallysubstituted alkyl or aralkyl groups, or Y₁ is an oxy group O—Y₄, Y₄being an optionally substituted alkyl or arylalkyl or aryl group, and Y₂and Y₃ independently of one another are alkyl or arylalkyl groups eachof which may optionally be substituted, or Y₁ and Y₂ are joined to oneanother to form a carbocyclic or heterocyclic ring which has a ring sizeof between 5 and 8, preferably 6, atoms and optionally has one or twosingly unsaturated bonds, and Y₃ is an optionally substituted alkyl orarylalkyl group.
 3. A two-component polyurethane composition as claimedin claim 1, characterized in that the aldehyde has the formula

where Y₅ is an optionally substituted aryl or heteroaryl group which hasa ring size of between 5 and 8, preferably 6, atoms.
 4. A two-componentpolyurethane composition as claimed in claim 1, characterized in thatthe aldehyde has the formula

where R¹ alternatively is a linear or branched alkyl chain, optionallycontaining at least one heteroatom, in particular containing at leastone ether oxygen, or is a mono- or polyunsaturated linear or branchedhydrocarbon chain; or is

where R² is a linear or branched or cyclic alkylene chain, optionallycontaining at least one heteroatom, in particular containing at leastone ether oxygen, or is a mono- or polyunsaturated linear or branched orcyclic hydrocarbon chain, and R³ is a linear or branched alkyl chain. 5.A two-component polyurethane composition as claimed in claim 4,characterized in that the aldehyde has the formula

where R¹ alternatively is a linear or branched alkyl chain having 11 to30 carbon atoms, optionally containing at least one heteroatom, inparticular containing at least one ether oxygen, or is a mono- orpolyunsaturated linear or branched hydrocarbon chain having 11 to 30carbon atoms; or is

where R² is a linear or branched or cyclic alkylene chain having 2 to 16carbon atoms, optionally containing at least one heteroatom, inparticular containing at least one ether oxygen, or is a mono- orpolyunsaturated linear or branched or cyclic hydrocarbon chain having 2to 16 carbon atoms, and R³ is a linear or branched alkyl chain having 1to 8 carbon atoms.
 6. A two-component polyurethane composition asclaimed in claim 4, characterized in that the aldehyde used forpreparing the polyaldimine is obtainable by an esterification reactionof 3-hydroxypivalaldehyde with a carboxylic acid, in particular withoutusing a solvent, 3-hydroxypivalaldehyde being prepared if desired insitu from formaldehyde, or paraformaldehyde, and isobutyraldehyde.
 7. Atwo-component polyurethane composition as claimed in claim 6,characterized in that the carboxylic acid used for preparing thealdehyde is selected from the group consisting of lauric acid, myristicacid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenicacid, succinic acid, adipic acid, azelaic acid and sebacic acid.
 8. Atwo-component polyurethane composition as claimed in claim 1,characterized in that the polyamine containing aliphatic primary aminogroups is selected from the group consisting of1,6-hexaamethylenediamine, MPMD, DAMP, IPDA,4-aminomethyl-1,8-octanediamine, 1,3-xylylenediaamine,1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane,bis(4-amino-3-methylcyclohexyl)methane,3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0^(2,6)]decane,1,4-diamino-2,2,6-trimethylcyclohexane, polyoxyalkylene-polyamineshaving theoretically two or three amino groups, especially Jeffamine®EDR-148, Jeffamine® D-230, Jeffamine® D-400 and Jeffamine® T-403, andalso mixtures of two or more of the aforementioned polyamines.
 9. Atwo-component polyurethane composition as claimed in claim 1,characterized in that for preparing the polyaldimine the aldehyde isused stoichiometrically or in a stoichiometric excess in relation to theprimary amino groups of the polyamine.
 10. A two-component polyurethanecomposition as claimed in claim 1, characterized in that the polyol forpreparing the polyurethane prepQlymer has an average OH functionality offrom 1.6 to
 3. 11. A two-component polyurethane composition as claimedin claim 10, characterized in that the polyol is a polyoxyalkylenepolyol, in particular a polyoxyalkylene diol or polyoxyalkylene triol,in particular a polyoxypropylene diol or polyoxypropylene triol or anEO-endcapped polyoxypropylene diol or triol.
 12. A two-componentpolyurethane composition as claimed in claim 10, characterized in thatthe polyol is a polyoxyalkylene polyol having a degree of unsaturation<0.02 meq/g and a molecular weight M_(n) of from 1000 to 30 000 g/mol.13. A two-component polyurethane composition as claimed in claim 12,characterized in that the polyol is a polyol prepared by means of DMCcatalysis.
 14. A two-component polyurethane composition as claimed inclaim 1, characterized in that the polyurethane prepolymer and thepolyaldimine are in a ratio of from 0.1 to 1.1, in particular from 0.5to 1.1, preferably in a ratio of from 0.6 to 0.9 equivalent of aldiminegroups per equivalent of isocyanate groups.
 15. A two-componentpolyurethane composition as claimed in claim 1, characterized in thatthe carrier material of the second component (B) is a polymer containingionic groups.
 16. A method of mixing a two-component polyurethanecomposition as claimed in claim 1, characterized in that the mixingratio of the first component (A) to the second component (B) is chosensuch that the ratio of equivalent of water to equivalent of aldiminegroups is from 0.5 to 10.0, in particular from 1.0 to 5.0.
 17. A methodof mixing as claimed in claim 16, characterized in that the twocomponents are mixed essentially homogeneously.
 18. A method of mixingas claimed in claim 16, characterized in that the two components aremixed in an essentially layerlike manner.
 19. A method of mixing asclaimed in claim 16, characterized in that the mixing of the twocomponents (A) and (B) takes place by means of a metering attachmentcomprising two interengaging metering rotors, and also, if desired,additionally by means of a static mixer mounted at the exit aperture ofthis metering attachment.
 20. A process for applying a two-componentpolyurethane composition as claimed in claim 1, characterized in that itcomprises the following steps: mixing the two components (A) and (B)contacting at least one solids surface with the mixed polyurethanecomposition curing the mixed polyurethane composition.
 21. A process forapplying as claimed in claim 20, characterized in that the contacting ofthe solids surface takes place by applying a bead to the surface.
 22. Aprocess for applying as claimed in claim 20, characterized in that themixing of the two components (A) and (B) takes place by means of ametering attachment comprising two interengaging metering rotors, andalso, if desired, additionally by means of a static mixer mounted at theexit aperture of this metering attachment.
 23. A process as claimed inclaim 22, characterized in that the metering attachment is mounted on acommercially customary cartridge which comprises the first component(A), and the second component (B) is in a container integrated in themetering attachment.
 24. The use of a two-component polyurethanecomposition as claimed in claim 1 as an adhesive, sealant or covering,in particular as an adhesive or sealant.
 25. A process for preparing atwo-component polyurethane composition as claimed in claim 1,characterized in that it comprises a step of preparing a polyaldiminefrom an aldehyde and a polyamine.